scholarly journals Heterogeneity formation within biofilm systems

2018 ◽  
Vol 29 (6) ◽  
pp. 1020-1034 ◽  
Author(s):  
ANDREAS C. ARISTOTELOUS ◽  
YURY GRABOVSKY ◽  
ISAAC KLAPPER
Keyword(s):  
Linear Analysis ◽  
Length Scale ◽  
Diffusive Transport ◽  
Full Model ◽  
Transport Efficiency ◽  
Community Function ◽  
Functional Consequences ◽  
Scale Properties ◽  
Insight Into ◽  
Structural Heterogeneities

Biofilms, and collections of embedded microbial communities, present structural heterogeneities with functional consequences for important processes, such as transport. The origin of such structures has been unclear. Here, we propose that they can arise as a consequence of diffusive transport limitation. To illustrate, a model allowing internal heterogeneity is developed. Linear analysis is applied to a simplified version of the model suggesting that heterogeneity forms on (or below) the active layer length, a length scale that may not be suitable for homogenization, with non-trivial implications for system scale properties such as reduction in system-wide diffusive transport efficiency. Numerics suggest that the simplified model provides useful insight into behaviour of the full model. We then show examples based on microcolony formation in host domains and argue that internal heterogeneity can be related to community function.

Suction-Controlled Detachment of Mushroom-Shaped Adhesive Structures

2021 ◽  
Vol 88 (3) ◽  
Author(s):  
Marcela Areyano ◽  
Jamie A. Booth ◽  
Dane Brouwer ◽  
Luke F. Gockowski ◽  
Megan T. Valentine ◽  
...  
Keyword(s):  
Experimental Investigation ◽  
Critical Stress ◽  
Design Space ◽  
Asymptotic Result ◽  
Length Scale ◽  
System Parameters ◽  
Trapped Air ◽  
Attachment Strength ◽  
Remote Stress ◽  
Insight Into

Abstract Experimental evidence suggests that suction may play a role in the attachment strength of mushroom-tipped adhesive structures, but the system parameters which control this effect are not well established. A fracture mechanics-based model is introduced to determine the critical stress for defect propagation at the interface in the presence of trapped air. These results are compared with an experimental investigation of millimeter-scale elastomeric structures. These structures are found to exhibit a greater increase in strength due to suction than is typical in the literature, as they have a large tip diameter relative to the stalk. The model additionally provides insight into differences in expected behavior across the design space of mushroom-shaped structures. For example, the model reveals that the suction contribution is length-scale dependent. It is enhanced for larger structures due to increased volume change, and thus the attainment of lower pressures, inside of the defect. This scaling effect is shown to be less pronounced if the tip is made wider relative to the stalk. An asymptotic result is also provided in the limit that the defect is far outside of the stalk, showing that the critical stress is lower by a factor of 1/2 than the result often used in the literature to estimate the effect of suction. This discrepancy arises as the latter considers only the balance of remote stress and pressure inside the defect and neglects the influence of compressive tractions outside of the defect.

Transport in Pulsatile Axisymmetric Stented Arterial Models From Location-Dependent Variations in Permeability and Mechanical Properties

2011 ◽  
Author(s):  
Joseph T. Keyes ◽  
Bruce R. Simon ◽  
Jonathan P. Vande Geest
Keyword(s):  
Mechanical Properties ◽  
Drug Delivery ◽  
Relative Influence ◽  
Drug Eluting Stents ◽  
Diffusive Transport ◽  
Antiproliferative Effects ◽  
Drug Eluting ◽  
Tissue System ◽  
Localized Drug Delivery ◽  
Insight Into

Drug-eluting stents (DESs) perform their antiproliferative effects through the use of localized drug delivery. The delivery may be computationally modeled to determine efficacy of the DES-tissue system and utilizes coupled convective and diffusive transport. Since the movement of solutes through the wall is via the coupled effects of convective and diffusive transport, the relative influence of these factors provides insight into the governing forces of localized DES drug delivery [1].

Application of a Three-Dimensional Computational Wrist Model to Proximal Row Carpectomy

2015 ◽  
Vol 137 (6) ◽  
Author(s):  
Jennifer S. Wayne ◽  
Afsarul Q. Mir
Keyword(s):  
Wrist Joint ◽  
Three Dimensional ◽  
Proximal Row Carpectomy ◽  
Clinical Tool ◽  
Additional Insight ◽  
Bony Anatomy ◽  
Muscle Loading ◽  
Functional Consequences ◽  
Triangular Fibrocartilage ◽  
Insight Into

A three-dimensional (3D) computational model of the wrist examined the biomechanical effects of the proximal row carpectomy (PRC), a surgical treatment of certain wrist degenerative conditions but with functional consequences. Model simulations, replicating the 3D bony anatomy, soft tissue restraints, muscle loading, and applied perturbations, demonstrated quantitatively accurate responses for the decreased motions subsequent to the surgical procedure. It also yielded some knowledge of alterations in radiocarpal contact force which likely increase contact pressure as well as additional insight into the importance of the triangular fibrocartilage complex and retinacular/capsular structures for stabilizing the deficient wrist. As better understanding of the wrist joint is achieved, this model could serve as a useful clinical tool.

The relative diffusive transport rate of SrI2 in water changes over the nanometer length scale as measured by coherent quasielastic neutron scattering

2016 ◽  
Vol 18 (18) ◽  
pp. 12707-12715
Author(s):  
Kenneth A. Rubinson ◽  
Antonio Faraone
Keyword(s):  
Neutron Scattering ◽  
Transport Rate ◽  
Length Scale ◽  
Diffusive Transport ◽  
Distance Dependence ◽  
Quasielastic Neutron ◽  
Quasielastic Neutron Scattering ◽  
Nanometer Length Scale ◽  
Relative Motions

Neutron scattering has been used to measure the relative motions of ions in water as a function of the average separation between the ions and finds a complicated distance dependence that shows continuum hydrodynamics cannot apply on the nm length scale.

STUDY OF A PAIR OF COUPLED CONTINUUM EQUATIONS MODELING SURFACE GROWTH: INTERPLAY BETWEEN SURFACE DIFFUSION, DESORPTION-ACCRETION AND SCHWOEBEL BACK DIFFUSION

2004 ◽  
Vol 18 (10n11) ◽  
pp. 1549-1569
Author(s):  
AIN-UL HUDA ◽  
OMJYOTI DUTTA ◽  
ABHIJIT MOOKERJEE
Keyword(s):  
Surface Diffusion ◽  
Numerical Data ◽  
Length Scale ◽  
Back Diffusion ◽  
Mbe Growth ◽  
Crossover Behavior ◽  
Long Time ◽  
Large Length ◽  
Large Length Scale ◽  
Insight Into

In this communication we shall focus on the three microscopic processes whose interplay determine the surface morphology of MBE growth: namely, surface diffusion, desorption and accretion and Schwoebel back diffusion. We gain insight into the dynamics of growth via one-loop perturbative techniques. This allows us to analyze our numerical data. We conclude that there is a crossover behavior from a roughening regime to a very long-time, large length scale smoothening regime.

scholarly journals Insight into Evolution, Processing and Performance of Multi-length-scale Structures in Planar Heterojunction Perovskite Solar Cells

2015 ◽  
Vol 5 (1) ◽  
Author(s):  
Yu-Ching Huang ◽  
Cheng-Si Tsao ◽  
Yi-Ju Cho ◽  
Kuan-Chen Chen ◽  
Kai-Ming Chiang ◽  
...  
Keyword(s):  
Solar Cells ◽  
Perovskite Solar Cells ◽  
Length Scale ◽  
Scale Structures ◽  
And Performance ◽  
Planar Heterojunction ◽  
Insight Into

Insight into the Structure – Elastic properties relationship of calcium silicate glasses: multi-length scale approach

2021 ◽  
Author(s):  
Mohamed Naji ◽  
Othman El Kssiri ◽  
Sandra Ory ◽  
Aurélien Canizares ◽  
Mohammed Filali ◽  
...  
Keyword(s):  
Molecular Dynamics ◽  
Light Scattering ◽  
Molecular Dynamics Simulations ◽  
Elastic Properties ◽  
Calcium Silicate ◽  
Silicate Glasses ◽  
Length Scale ◽  
Dynamics Simulations ◽  
Relationship Of ◽  
Insight Into

Based on a combination of molecular dynamics simulations, Raman and Brillouin light scattering spectroscopies, we investigate the structure and elastic properties relationship in an archetypical calcium silicate glass system. From...

scholarly journals Caffeine, Nicotine and MDMA Effects on Retina suggestive of Potential Functional Consequences

2021 ◽  
pp. 1-12
Author(s):  
Joshua O. Owolabi ◽  
Philip O. Ogunnaike
Keyword(s):  
Body Weight ◽  
Reference Group ◽  
Juvenile Male ◽  
Psychoactive Substances ◽  
Gfap Expression ◽  
Functional Consequences ◽  
Group A ◽  
Higher Doses ◽  
The Brain ◽  
Insight Into

The implications of the use of psychoactive substances, that are usually abused on the retina are yet to be adequately explored. The retina is neural in nature. Most investigations on psychoactive agents have only studied their effects on the brain and behaviour. The mechanisms employed by these agents in producing their effects on the brain suggest that the retina, being neural, might also be significantly affected by the use of the substances. This research investigated the effects of the prolonged use of caffeine, nicotine and 4-methylenedioxymethamphetamine [MDMA] on the retina. Juvenile male experimental Wistar were grouped and administered the lower and higher dose of each agent while a reference group remained as the Group A. Groups B and C received the lower [30mg/kg body weight]and the higher [50mg/kg body weight]doses of caffeine respectively; Groups D and E received the lower [10mg/kg body weight] and higher [20mg/kg body weight] doses of nicotine respectively while Groups F and G received the lower [20 mg/kg body weight] and the higher [40 mg/kg body weight] doses of MDMA respectively. The substances had effects on the thickness of the retina with higher doses in each instance causing reductions in retina thickness; the patterns of GFAP expression were also aberrant with the MDMA treated groups being most aberrant. There was no sign of extensive loss of any type of retinal cells. Rhodopsin expression generally demonstrated active rods and provided insight into relatively heathy cones. There is evidence that these agents altered retina thickness and GFAP expression but without extensive disruptions to serve as pathological hallmarks of retina degeneration. The consequences of these might be further investigated.

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